For butt joints with unequal thicknesses, should the weld thickness at the flange trimming area be considered to be greater than the minimum forming thickness of the flange?
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This post was last edited by megaherz_IGGE on 2023-12-22 at 16:49. Dear teachers, as shown in the figure, the head is thick while the cylinder is thin; the nominal thickness of the head is 34 mm, the minimum formable thickness of the head is 29.7 mm, and the thickness of the cylinder is 28 mm. Now that the head is being aligned with the cylinder, the straight edges of the head need to be trimmed. In this case, should the thickness B at the weld joint after trimming those straight edges be 29.7 mm or 28 mm? Is it necessary to ensure that the thickness B of the trimmed area is greater than the minimum required thickness for the formation of the head? Or in other words, when the calculated thickness of the head is greater than that of the cylinder, should the thickness at the cut edge of the straight edge section of the head be greater than the calculated thickness of the head, or greater than the calculated thickness of the cylinder?
After trimming, the thickness of the end cap with straight edges should be the same as that of the cylinder. It is advisable to leave some margin from the starting point of the arc on the end cap when trimming. If the length of the straight edges is not sufficient for trimming, those edges can be extended by customizing the end cap.
In this case of butt joints with unequal thicknesses, the weld thickness after trimming the head should be at least equal to or greater than the thickness of the cylinder, namely 28 mm. The minimum forming thickness of the head is typically a requirement to ensure the quality of its formation, while welding design focuses on the strength and sealing performance of the welds; therefore, the thickness after trimming should be sufficient to meet the requirements of the welded joint design. In practical operations, relevant welding specifications and design standards should be followed. If the design standards or engineering requirements specify that the edge trimming thickness must be greater than the minimum forming thickness of the head, then this requirement must be followed ； If no specific provisions are given, ensuring welding quality and joint strength should be the primary considerations. Generally, the thickness of the bevel on the head does not necessarily have to be greater than the minimum forming thickness of the head; it is sufficient as long as the strength of the weld joint is ensured. In general, the edge trimming thickness of the head during welding should be greater than or equal to the thickness of the cylinder, and it must also comply with design specifications and project requirements. If in doubt, it is recommended to consult a professional welding engineer or refer to relevant standards to determine the appropriate butt joint thickness. .
The flange trimming should be as thick as the thickness of the cylinder body
The straight edge section of the head has a calculated thickness; the minimum thickness of the head is different from this calculated thickness for the straight edge section, and it is sufficient as long as it is not less than its own calculated thickness
The straight-edge section of the head is definitely designed with reference to the cylinder; the thickness of this straight-edge section must be greater than or equal to the thickness required for the cylinder.
In the owner’s example, according to 6.5.3 of GB/T150.3 for chamfering, the end of the head should be chamfered to the designed thickness of the head. Theoretically, it’s also possible to reduce it to 28mm.